This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. This multi-center study is designed to determine the safety and efficacy of intraportal islet transplantation in patients with difficult to control type 1 diabetes using islets isolated by the two-step method and a glucocorticoid-free immunosuppressive regimen. Patients will be carefully monitored for the development of adverse events related to the procedure. Detailed metabolic follow-up tests will also be conducted frequently during the two-year follow-up to assess islet graft function, including IVGTT, arginine stimulation test, OGTT, glucose clamp, and insulin oscillation studies. This application requests support for subjects transplanted at Harbor-UCLA as well as support for laboratory measurements for the entire consortium. The lab support requested is to measure glucose, insulin, C-peptide, proinsulin and glucagon drawn during these procedures. Funding from the NCRR/JDRF covers the cost of islet preparation only, and does not support clinical aspects of this trial.